1. Field of the Invention
The present invention relates to a flexure chain blank sheet for a disk drive suspension used for manufacturing a flexure of a disk drive suspension.
2. Description of the Related Art
A hard disk drive (HDD) is used in an information processing apparatus, such as a personal computer. The hard disk drive comprises a magnetic disk rotatable about a spindle, a carriage turnable about a pivot, etc. On an arm of the carriage, a disk drive suspension (which will be hereinafter simply referred to as a suspension) is provided. The suspension comprises elements such as a load beam, and a flexure disposed to overlap the load beam. A magnetic head including a slider is mounted on a gimbal portion formed near a distal end of the flexure. The magnetic head is provided with elements for accessing data, that is, for reading and writing data. The load beam and the flexure, etc., constitute a head gimbal assembly.
Various types of flexures have been put to practical use according to the required specification. As an example of a flexure, a flexure with conductors is known. The flexure with conductors includes a metal base made of a thin stainless steel plate, an insulating layer made of an electrically insulating material, such as polyimide, which is formed on the metal base, a plurality of conductors formed on the insulating layer, etc. The flexure includes a proximal portion which overlaps the load beam, and a tail portion (a flexure tail) which extends toward the rear of a baseplate.
Conventionally, as a means for enhancing the manufacturing efficiency of the flexure, a flexure chain blank sheet disclosed in, for example, JP 5,273,271 B (Patent Literature 1) and JP 5,365,944 B (Patent Literature 2) is known. In order to manufacture the flexure chain blank sheet, a number of flexure elements having the same shape are formed by etching a stainless steel plate, for example. An example of the flexure chain blank sheet is constituted by arranging a plurality of frame units longitudinally relative to the flexure elements. Each of the frame units is constituted by a frame portion and a number of flexure elements arranged at a predetermined pitch within the frame portion.
The frame portion of the flexure chain blank sheet commonly includes a pair of lengthwise frames that agrees with the longitudinal direction (dimension) of the flexure element, and a pair of lateral frames that agrees with the lateral direction (dimension) of the flexure element. In these lengthwise frames or lateral frames, positioning holes to be used in positioning the flexure chain blank sheet in the manufacturing process of the flexure may be formed at several places. For example, when a positioning hole is formed in the lateral frame, the width of the lateral frame (the dimension which is orthogonal to the longitudinal dimension of the lateral frame) must be made greater than the outside diameter of the positioning hole. However, the greater the width of the lateral frame is, the greater the length of the flexure chain blank sheet becomes. In order to reduce the width of the lateral frame, the positioning hole may be made smaller, but in that case, the positioning pin must also be made small. Reduction in the size of the positioning pin has a limit.
Depending on an apparatus or a jig to be used in the manufacturing process of the flexure, the size (outer dimensions) of a single flexure chain blank sheet may be restricted. Accordingly, if the length of the flexure chain blank sheet is increased in even the slightest terms, the number of frame units which can be formed in a flexure chain blank sheet must be reduced by one. In one frame unit, since a number of (several tens of to several hundreds of) flexure elements which are formed by etching are arranged at a predetermined pitch, reducing the frame unit by one means reducing several tens of to several hundreds of flexures per flexure chain blank sheet. Accordingly, there arises a problem that the manufacturing efficiency of flexures is drastically reduced.